U.S. patent number 6,405,602 [Application Number 09/610,939] was granted by the patent office on 2002-06-18 for machine for inspecting ceramic samples by applying compression thereto.
This patent grant is currently assigned to NGK Insulators, Ltd.. Invention is credited to Nobuo Itou, Shinichi Naruse, Mitsuo Takahashi.
United States Patent |
6,405,602 |
Itou , et al. |
June 18, 2002 |
Machine for inspecting ceramic samples by applying compression
thereto
Abstract
A machine for inspecting a ceramic sample by applying a
compression thereto, includes an inspecting container including a
generally cylindrical container provided with an elastic sleeve
therein. An elastic sheet is disposed between the cylindrical
container and the elastic sleeve. The cylindrical container and the
elastic sleeve and sheet are integrated to form the inspecting
container. A ceramic sample provided in the cylindrical container
is compressed by injecting a hydrostatic pressure applying medium
between the elastic sheet and the cylindrical container.
Inventors: |
Itou; Nobuo (Mie-gun,
JP), Naruse; Shinichi (Nagoya, JP),
Takahashi; Mitsuo (Nagoya, JP) |
Assignee: |
NGK Insulators, Ltd.
(JP)
|
Family
ID: |
16649620 |
Appl.
No.: |
09/610,939 |
Filed: |
July 6, 2000 |
Foreign Application Priority Data
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Jul 28, 1999 [JP] |
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11-214061 |
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Current U.S.
Class: |
73/818;
73/790 |
Current CPC
Class: |
G01N
3/10 (20130101); G01N 2203/0256 (20130101); G01N
2203/0284 (20130101); G01N 2203/0286 (20130101) |
Current International
Class: |
G01N
3/10 (20060101); G01N 3/00 (20060101); G01N
3/02 (20060101); G01N 003/08 () |
Field of
Search: |
;73/807,813,818,825,826 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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45-8944 |
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Apr 1970 |
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JP |
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59-14048 |
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Jan 1984 |
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JP |
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60-129641 |
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Jul 1985 |
|
JP |
|
6-69815 |
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Sep 1994 |
|
JP |
|
10-197429 |
|
Jul 1998 |
|
JP |
|
Primary Examiner: Fuller; Benjamin R.
Assistant Examiner: Allen; Andre
Attorney, Agent or Firm: Parkhurst & Wendel, LLP
Claims
What is claimed is:
1. A machine for inspecting a ceramic sample by applying a
compression force thereto, comprising:
an inspecting container including a generally cylindrical container
provided with an elastic sleeve therein;
an elastic sheet disposed between said cylindrical container and
said elastic sleeve; and
means for compressing a ceramic sample in said cylindrical
container by injecting a hydrostatic pressure applying medium
between said elastic sheet and said cylindrical container at a high
rate of change in pressure and at a low rate of change in pressure,
wherein said elastic sleeve is capable of and positioned for
contacting such a sample at said high rate of change in pressure
and then compressing such a sample at said low rate of change in
pressure, and said cylindrical container, said elastic sheet and
said elastic sleeve are integrated to form said inspecting
container.
2. The machine of claim 1, further comprising means for determining
the beginning of sample fracture by detecting a sound from the
sample and suspending compression thereof.
3. The machine of claim 1, wherein the sample comprises a honeycomb
structure.
4. The machine of claim 1, wherein said elastic sheet a said
elastic sleeve are each made of urethane.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inspection machine by
compression for ceramic samples, and in particular, for ceramic
samples having honeycomb structures.
2. Description of Related Art
Inspections by compression on a ceramic structure, such as a
honeycomb structure, is performed by applying hydrostatic pressure
on the ceramic structure. FIG. 4 is a perspective view of a
conventional inspection method by compression having a
configuration in which a sample 1, disposed in a urethane rubber
cylinder 2 having an internal diameter corresponding to the
diameter of the sample 1 and having a thickness of 1 to 2 mm, is
provided with disk-like acrylic plates 3 attached to the sample 1
at the ends thereof, the acrylic plates 3 are fixed to the urethane
rubber cylinder 2 by elastic bands 4, and the sample 1 covered by
the urethane rubber cylinder 2 and the acrylic plates 3 is placed
in water in a tank 5, whereby pressure is applied to the sample
1.
However, a problem in the above-described conventional inspection
method by compression has been found to be that the efficiency of
operation decreases when many samples are inspected because it is
time-consuming to fix the acrylic plates 3 to the urethane rubber
cylinders 2 by the elastic bands 4. Another problem is that it is
difficult to clean the inspection device after inspecting when wet
fractions of samples, which have been broken by the pressure,
adhere to the urethane rubber cylinders.
In order to overcome these problems, an inspection machine by
compression is disclosed in, for example, Japanese Unexamined
Patent Application Publication No. 10-197429, in which the
inspection machine is provided with a cylindrical container, a
urethane sleeve, and a urethane sheet. Inspecting using this
inspection machine by compression is performed as follows.
Referring to FIG. 5, a sample 1 provided with a urethane sleeve 7
around the same is placed in a cylindrical container 8 with a
urethane sheet 9 disposed between the urethane sleeve 7 and the
cylindrical container 8. A hydrostatic-pressure-applying medium is
injected between the cylindrical container 8 and the urethane sheet
9, thereby compressing the sample 1 at the periphery thereof,
whereby the inspection by compression is performed.
In this inspection machine by compression, the sample 1 is not
fixed by elastic bands. Therefore, the efficiency of operation is
not decreased when many samples are processed. Moreover, after
inspecting, dry fractions of the sample 1 remain in the urethane
sleeve 7. Therefore, cleaning of the inspection machine is easier
than when using the urethane rubber cylinder 2 shown in FIG. 4.
However, a problem in the inspection machine by compression 1 shown
in FIG. 5 is that it is difficult to control the pressure applied
to the sample 1, because the compression of the sample 1 does not
properly respond to the pressure applied to the pressure-applying
medium due to the elasticity of the urethane sleeve 7.
Another problem is that it is difficult to apply a low pressure of
not greater than 10 kg/cm.sup.2 to the sample 1 due to the
elasticity of the urethane sleeve 7. That is, when the pressure on
the sample 1 is desired to be at a pressure of 10 kg/cm.sup.2 or
less, the pressure applied to the pressure-applying medium serves
only to compress the urethane sleeve 7 and does not compress the
sample 1.
Yet another problem has been found in the inspection machine by
compression 1 shown in FIG. 5, in that a tact time of the test must
be set to be long when a high pressure is applied to the sample 1,
because there is a time lag before a pressure-load reaches the
sample 1 after the pressure is applied to the inspection machine,
the time lag being caused by the elasticity of the urethane sleeve
7, thereby reducing the efficiency in the operation. Furthermore,
when a high pressure-load is applied in a short time, there is a
risk of breaking the sample 1 by the shock of the pressure.
Generally, when a lot of samples are inspected at high pressures,
tact time required per sample for the inspection must be reduced so
as to increase the efficiency of the inspection.
In the inspection machine by compression 1 shown in FIG. 5, the
preparations for the inspection are laborious, in which each sample
must be inserted to the urethane sleeve 7, then must be disposed in
the cylindrical container 8. An easy method for cleaning the
fractions of the sample 1 is also necessary.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an
inspection machine by compression in which inspection operation and
cleaning of the inspection machine are easy, application of a low
pressure is possible, and a tact time required per sample for the
inspection is reduced, thereby increasing the efficiency of the
inspection.
To these ends, an inspection machine by compression for inspecting
a ceramic sample is provided, in which the ceramic sample covered
by an elastic sleeve disposed at the periphery of the sample is
received in a cylindrical container across an elastic sheet
provided between the cylindrical container and the elastic sleeve,
and the ceramic sample is compressed by a
hydrostatic-pressure-applying medium injected between the
cylindrical container and the elastic sheet. The sample is received
in an inspecting container provided with the cylindrical container
including the elastic sleeve and the elastic sheet between the
elastic sleeve and an inner wall of the cylindrical container.
In the inspection machine by compression according to the
invention, the elastic sleeve is preferably brought into contact
with the sample by high-speed-pressurizing, and may be compressed
so as to apply pressure to the sample by low-speed-pressurizing. In
the inspection machine by compression, the beginning of fracture of
the sample is preferably determined by detecting fracture sound
from the sample, thereby suspending pressurization.
In the inspection machine by compression according to the
invention, the sample may have a honeycomb structure. The elastic
sheet and the elastic sleeve may be made of urethane.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic section of an inspection machine by
compression according to an embodiment of the present
invention;
FIG. 2A is a schematic plan view of an inspection machine by
compression according to another embodiment of the present
invention;
FIG. 2B is a schematic plan view of an inspection machine by
compression according to yet another embodiment of the present
invention;
FIGS. 3A, 3B, 3C, and 3D are graphs showing pressure curves when
inspecting by using the inspection machine by compression according
to the present invention, in which the maximum load values are set
to 5 kg, 7 kg, 10 kg, and 15 kg, respectively;
FIG. 4 is a perspective view of a known inspection machine by
compression;
FIG. 5 is a schematic section of another known inspection machine
by compression; and
FIG. 6 is a schematic section of the inspection machine by
compression according to the present invention, by the use of which
an inspection is performed.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In an inspection machine by compression according to an embodiment
of the present invention, a ceramic sample provided with an elastic
sleeve around the same is disposed in a cylindrical container
across an elastic sheet between the elastic sleeve and the
cylindrical container, and a hydrostatic-pressure-applying medium
is injected between the cylindrical container and the elastic sheet
and is pressurized, whereby an inspection by compression is
performed on the ceramic sample. As shown in FIG. 1, a sample 1 is
received in an inspecting container 15 including a cylindrical
container 8, an elastic sleeve 7, and an elastic sheet 9 disposed
between the cylindrical container 8 and the elastic sleeve 7. Since
the cylindrical container 8, the elastic sheet 9, and the elastic
sleeve 7 are assembled to form an inspecting container 15, it is
not necessary to insert each sample 1 to the urethane sleeve 7, and
to insert the urethane sleeve 7 containing the sample 1 to the
cylindrical container 8. Therefore, this is prepared in a manner
simpler than in a conventional inspecting machine by compression
shown in FIG. 5. In the inspecting machine by compression according
to the embodiment of the invention, the pressure rise is suspended
by detecting a fracture sound from the inspecting sample;
therefore, the sample is not broken further than is necessary,
whereby fractions of the sample can be easily cleaned compared with
the conventional inspection machine by compression shown in FIG.
5.
In the inspection machine by compression according to the present
invention, the elastic sleeve 7 is preferably pressed to the sample
1 at a high-speed pressurizing of 2 to 6 kg/cm.sup.2 /second, and
is preferably pressed so as to compress the sample 1 at a low-speed
pressurizing of 0.5 to 1 kg/cm.sup.2 /second, wherein "high-speed
pressurizing" and "low-speed pressurizing" means respective high
and low rates of change in pressure. By applying pressure in steps
at different pressurizing speeds, an efficient inspection in a
short tact time is possible when applying a high pressure. The high
pressurizing speed is possible due to the fact that there is no
risk of fracturing the sample 1 by the shock at high pressurizing
speed, because the sample 1 is not pressed by the elastic sleeve 7
for a time after the pressurizing starts until the elastic sleeve 7
presses the sample 1, the time lag being produced by the elasticity
of the elastic sleeve 7. With this arrangement, a tact time per
sample is conveniently reduced. When the elastic sleeve 7 is
compressed to press the sample 1, a load starts to be applied to
the sample 1; therefore, the pressure must be applied at a low
speed so as to avoid fracturing the sample 1 due to shocks.
With this arrangement in which the pressure is applied in steps,
time saving by pressing the elastic sleeve 7 to the sample 1 at a
high speed can be realized together with low-speed pressurizing
which is required for applying a low pressure-load to the sample 1.
A maximum pressure is obtained by the low-speed pressurizing,
thereby improving response of the pressure applied to the sample 1
to the pressure applied to the elastic sleeve 7. The timing of
switching from the high-speed pressurizing to the low-speed
pressurizing is determined by detecting the mechanical position of
a cylinder head for producing compression to apply hydrostatic
pressure between the cylindrical container 8 and the elastic sheet
9, or by detecting the hydrostatic pressure value. FIGS. 3A to 3D
are graphs showing pressure curves in accordance with the elapse of
time when the maximum load value is set to 5 kg, 7 kg, 10 kg, and
15 kg, respectively. In each graph, a solid line represents values
of pressure applied to the sample and measured by a load cell, and
dotted lines represent values of hydrostatic pressure detected by a
pressure sensor.
The inspection machine by compression according to the present
invention preferably determines the start of fracture of the sample
by detecting a fracture sound from the sample, thereby suspending
pressurizing. The sample is prevented from being unnecessarily
broken by suspending pressurizing when the start of fracture of the
sample is detected either by detecting a fracture sound at the
beginning of fracture of the ceramic sample by an acoustic emission
(AE) sensor, or by detecting the change in hydrostatic pressure due
to the fracture of the sample, whereby excessive fracturing of the
sample does not occur, thereby making cleaning easier.
FIG. 2A. is a plan view of an inspection machine by compression 6
according to another embodiment of the present invention, in which
four inspecting containers 15 are provided, samples are loaded and
unloaded to and from the inspection machine by compression 6 at one
position, the pressure is applied at one position, and an operator,
without changing his/her position, can perform the inspection by
compression successively by turning the four inspecting containers.
FIG. 2B is a plan view of an inspection machine by compression 6
according to yet another embodiment of the present invention, in
which eight inspecting containers 15 are provided in four pairs,
and samples are loaded into and unloaded from the inspection
machine by compression 6, and the pressure is applied at one
position. Two samples received in a pair of the inspecting
containers 15 are inspected concurrently, thereby making the
inspection efficient.
The inspection machine by compression according to the present
invention is preferably used for an inspection by compression for
ceramic samples, in particular, for an inspection by compression of
ceramic honeycomb structures.
The present invention is described below with reference to an
experimental operation performed by using an example of the
inspection machine by compression according to the invention. It is
to be understood that the invention is not limited to this
example.
Referring to FIGS. 1 and 6, an inspection by compression of a
ceramic honeycomb structure was performed by using an inspection
machine by compression 6 including an inspecting container 15
having a cylindrical container 8, a urethane sheet 9, and a
urethane sleeve 7.
The cylindrical container 8 made of iron is provided with the
urethane sheet 9 having a thickness of 2 to 5 mm at an inner side
of the cylindrical container 8. The urethane sheet 9 is
hermetically fixed to the cylindrical container 8 by being clamped
at each side of the urethane sheet 9 by an annular edge and a
flange 13 formed at each end of the cylindrical container 8 and by
screws 12 passing through the annular edge and the flange 13. The
urethane sleeve 7 having a thickness of 10 to 30 mm is disposed at
the inner side of the urethane sheet 9. The urethane sleeve 7 is
fixed to the cylindrical container 8 by coupling therewith. The
cylindrical container 8 is provided with an air outlet 14 and a
pressure inlet 16 connectable with a pressure hose of a compressing
unit (not shown).
During inspecting, the inspecting container 15 was fixed to a base
17, as shown in FIG. 6. A supporting cylinder 11 was moved to the
upper level of the cylindrical container 8, a honeycomb structure 1
was mounted on the supporting cylinder 11, the supporting cylinder
11 was moved down to the lower level of the inspecting container
15, and the honeycomb structure 1 was thus received in the
inspecting container 15. A retaining cylinder 10 was disposed on
the honeycomb structure 1, and the supporting cylinder 11 and the
retaining cylinder 10 clamped the honeycomb structure 1 with a
force of approximately 10 kgf/cm.sup.2 so that the honeycomb
structure 1 did not move with the pressure applied thereto.
Water was injected between the cylindrical container 8 and the
urethane sheet 9 through an injecting valve (not shown) being
released. While injecting water, the air between the cylindrical
container 8 and the urethane sheet 9 was released through the air
outlet 12, and the air outlet 12 was closed after the water was
injected. Then, the compressing unit (not shown) started to apply
pressure through the pressure hose. The pressure was applied for a
second by a high-speed pressurizing of 5 kg/cm.sup.2 /second to a
level of 5 kg/cm.sup.2, thereby pressing the urethane sleeve 7 to
the honeycomb structure 1 and compressing the urethane sleeve
7.
Next, the honeycomb structure l started to be compressed by a
low-speed pressurizing of 1 kg/cm.sup.2 /second. The timing of
switching from the high-speed pressurizing to the low-speed
pressurizing was determined by detecting the mechanical position of
a cylinder head for producing compression for applying hydrostatic
pressure between the cylindrical container 8 and the elastic
urethane sheet 9. When the pressure was applied, the urethane
sleeve 7 came into contact with the periphery of the honeycomb
structure 1, thereby evenly pressing the entire periphery thereof.
FIG. 6 shows the inspection machine by compression 6 while
performing the inspection. In the inspection, the honeycomb
structure 1 cracked when the pressure rose to 5 kg/cm.sup.2 in one
second; therefore, the pressurizing was suspended, and the pressure
was reduced. The cracking was detected by an AE sensor (not shown)
provided on the retaining cylinder 10.
By using the above-described inspection machine by compression
according to the present invention, an inspection by compression
can be easily performed compared with the case in which a
conventional inspection machine by compression is used, thereby
increasing the efficiency of the test. In the inspection machine by
compression, a sample is not broken more than necessary because
pressure-rise is suspended by detecting a fracture sound from the
sample, whereby fractions of the sample can be cleaned up
easily.
In the inspection machine by compression according to the present
invention, when the pressure is applied in steps, a test under a
low pressure is possible, and an efficient inspection in a short
tact time is also possible when a high pressure is applied. The
response in the pressure rise on the sample to the pressure applied
to a pressure-applying medium can be improved, thereby facilitating
control of the pressure applied to the sample.
In the inspection machine by compression according to the present
invention, the beginning of breakage of a sample is detected by
sensing fracture sound from the sample, and the pressure-rise is
suspended, thereby avoiding unnecessary breakage of the sample,
whereby fractions of the sample can be cleaned up more easily.
* * * * *